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May 27, 2016

Previewing H.264/AVC support for ORTC

Today we’re excited to announce preliminary support for H.264/AVC support in the real-time communications (RTC) stack in Microsoft Edge, as initially promised in our April roadmap update. You can preview this feature in Windows Insider Preview builds starting with EdgeHTML 14.14352 by navigating to about:flags and checking “Enable experimental H.264/AVC support.” This change helps enable interoperable video communications solutions across browsers for basic 1:1 calling scenarios.

This preview release adds the following for H.264/AVC support in our RTC stack:

  • Support for packetization-mode 1, per RFC 7742
  • Support for Constrained Baseline Profile with levels up to 4.2 (i.e. with profile-level-id=42c02a)
  • Support for the absolute send time header extension (abs-send-time)
  • Support for Picture Loss Indication (PLI), per RFC 4585 

H.264/AVC support is currently available through the ORTC API in Microsoft Edge.  In addition, we’re actively working with the community to enable these features via the adapter.js library as well.

These features lay the foundation for video interoperability within the Edge RTP stack, and we plan to extend this in future release by supporting additional feedback messages (e.g. Generic NACK) as well as congestion control and robustness mechanisms (e.g. RTX).

We will continue developing our RTC implementation beyond this summer’s Anniversary Update, including planned support for the WebRTC 1.0 API, and will share updates and preview builds as this work progresses.

– Shijun Sun, Principal Program Manager, Microsoft Edge
– Bernard Aboba, Principal Architect, Skype